Signals acquired from relatively simple systems can be viewed and understood using two-dimensional graphing techniques that represent electrical activity at one or more nodes in a circuit under test. Testing of more complex systems requires that many nodes (often hundreds) be viewed, and the information content and different timing relationships of these signals must be presented to the user.
A problem arises because different measurement instruments are used to gather information in different measurement domains, and each measurement domain provides a different view of circuit activity over time. For example, an oscilloscope provides representations of electrical phenomena associated with a circuit node, a logic analyzer provides representations of information content (i.e., logic level and transition timing) on a (typically) related set of nodes, and a spectrum analyzer represents the intensity or energy associated with each of a plurality of frequency components. Unfortunately, it can be difficult for a user to correlate information derived from each of the measurement domains to arrive at a higher level of understanding of the operation or failure of a system under test.
What is needed is a method and apparatus for combining the measurement results from the different measurement domains into a correlated, and easy to understand display.